Watchcase



y 1946. w. SCHMITZ v 2,399,832

WATCHGASE Filed April 28, 1942 z .QH-Jnii'I'ii'I'I IIIIIIIIlllllilllmm lllllllllllllllllllllm "III Patented May 7, 1946 Werner Schmitz, Grenchen, Switzerland Application April 28, 1942, Serial No. 440,868 In Switzerland September 26, 1941 2 Claims. (Cl. 58-91) In so-called fancy watch cases, i. e., in watch cases of polygonal contour, it is difllcult to obtain watertightness between crystal and bezel if the parts between which the crystal is clamped are not flat. It requires much care and precision on the part of the casemakers to obtain in curved watch cases a precise and perfectly equal clamping of the crystal over the whole periphery of the bezel.

The object of the present invention is a method for manufacturing watertight fancy watch cases which, even using hand lathes within the reach of every worker, permits a precision in making the parts clamping the crystal to be obtained which was hitherto very rare. This method is characterised in that all the parts holding the crystal are formed by portions of the envelope of cones having the same apex angle. This angle may be obtained very exactly by forming a master die on a lathe. Not only the master dies of the watch cases but also the matrixes and punches can be made by this invention with a precision necessary for perfectly clamping the crystal between two exactly parallel surfaces.

The tools for carrying out the method are characterised in that their active part is formed by portions of the envelope of imaginary cones having the same apex angle, the side faces of the master die and the punch being perpendicular to the base of the said cone.

The watertight watch-case manufactured by this method is distinguished by the feature that the upper edges of its bottom are turned conically, the inner side of the bezel being formed by portions of the envelope of a cone with the same apex angle, as said upper edges.

The stages of the method according to the invention are described with reference to the accompanying drawing showing some examples of watch cases manufactured according to this method, as well as some of the tools for carrying out the method.

Fig. 1 shows three projections of the master die of the watch case to be manufactured.

Fig. 2'is a top view of the bezel of a watch case to be manufactured,

Fig. 3 illustrates the pressing of the bezel,

Fig. 4 shows in a perspective view a first embodiment of the watch case,

Figs. 5 and 6 illustrate a second embodiment.

The master die for the watch case to be manufactured shown in Figure 1 is the basis serving for hollowing out the matrix and is made from a steel block 1 indicated by dotted lines, which, on a lathe, is given the conical form likewise marked by dotted lines.

The cone being finished, panes 2, 3 are milled on it to obtain the piece shown in the drawing which is the master die for a watch case curved on each side. This die, when tempered, is used for rectifying a matrix 4 (Fig. 3) from which the bezel is formed so that the part or bottom of the matrix which has to form the bezel, lies on the envelope of an imaginary cone whose apex 4 is situated on a perpendicular through the center of the watch case.

The punch 5 which is shown in Fig. 3 as having just finished the treatment of the bezel 6 in the interior of the matrix 4, is made in the same way as the master die, viz., on a lathe. After its temperlng it can be rectified on the same machine with any desired precision using conventional watch case making equipment. The punch and matrix may also be used to burnish the top of the bezel.

The case bottom 1, shown in Fig. 4 below the crystal 8 and the bezel 9, is first stamped by means of a matrix and a punch of well-known construction whose outer dimensions differ from one another by the thickness of the metal used. This bottom is then fixed to a chuck in such a way that the two diagonals of the bottom intersect each other in the center of the chuck; after this it is conically turned to the same angle as the punch of the bezel. Therefore, this case bottom has a surface formed of parts of the envelope of a like cone and the latter has at its apex exactly the same angle as that of the said punch. When the crystal, which has been formed in a tool made in the same manner as those for manufacturing bezel and bottom is brought into position, its rim is thereby clamped between two exactly parallel surfaces. In this way watertightness is obtained under most favorable conditions.

In the embodiment shown in Fig. 5 the case bottom 10 is likewise turned and rectified at its upper part, i. e., it makes contact with the crystal along an imaginary cone I l shown in dotted lines. The master die serving to obtain the matrix for the bezel represented is made in the same way as in the first example. Only the number of panes has been changed which, of course, can be arranged in any possible and desirable manner.

Fig. 6 illustrates, one above the other, the three parts, i. e., the bottom III, the crystal [6 and the bezel I! of the watch case according to Fig. 5.

Round watch cases can, without further ado, also be manufactured by this method.

What I claim is:

1. A watertight watch case having a. bottom, a die-pressed bezel and a crystal all of polygonal contour adapted to be held between said bottom and said bezel, characterized by the crystal contacting surfaces of said bezel and of said bottom consisting of parts of the envelopes of imaginary cones having the same apex angle and intersected by the plane sides of the polygonal contour.

2. A watertight watch case according to claim 1 wherein the imaginary cones have their apexes on 5 a perpendicular passing through the center of said bottom.

WERNER SCHMI'IZ. 

